Sigarilyas Psophocarpus tetragonolobus

About Sigarilyas

Sigarilyas, scientifically known as Psophocarpus tetragonolobus, is a tropical climbing legume belonging to the family Fabaceae. Known internationally as the winged bean, four-angled bean, or princess bean, it holds a unique distinction among food crops: every single part of the plant is edible and nutritious. The pods, leaves, flowers, tubers, and seeds all provide substantial food value, earning sigarilyas the reputation as one of the most complete food plants in the world.

The plant is a vigorous perennial vine that can grow 3 to 4 meters tall when given proper trellis support. Its most recognizable feature is the pod itself — a four-sided structure with distinctive wavy, ruffled "wings" running along each edge, giving the plant its common English name. These wing-shaped ridges make the pod unmistakable in any Philippine wet market. Young pods are crisp, slightly sweet, and have a texture somewhere between green beans and asparagus.

What truly sets sigarilyas apart from other vegetables is its extraordinary protein content. The mature seeds contain 30 to 40 percent protein — comparable to soybean — while the tuberous roots contain approximately 20 percent protein, far exceeding cassava, sweet potato, or any other tropical root crop. This exceptional nutritional profile led the U.S. National Academy of Sciences to identify the winged bean as one of the most promising crops for combating protein malnutrition in tropical developing countries, calling it a potential "supermarket on a stalk."

History and Discovery

Psophocarpus tetragonolobus was first formally described by the French botanist Augustin Pyramus de Candolle in 1825, based on earlier collections from tropical Asia. The genus name Psophocarpus comes from the Greek words psophos (noise) and karpos (fruit), referring to the sound the mature pods make when they split open. The species name tetragonolobus means "four-angled pod," describing the distinctive cross-section of the fruit.

The exact center of origin remains debated among botanists, but most evidence points to Papua New Guinea and Southeast Asia, including the Philippines, as part of the plant's native or very ancient cultivated range. Archaeological evidence suggests the winged bean has been cultivated in the region for thousands of years. It was already well established in Philippine agriculture long before Spanish colonization, and Filipinos developed numerous local varieties adapted to different growing conditions across the archipelago.

Sigarilyas gained international attention in the 1970s and 1980s when food scientists recognized its potential to address global protein deficiency. The National Academy of Sciences published a landmark report in 1975 identifying the winged bean as an underutilized crop with extraordinary nutritional value. In the Philippines, sigarilyas has always been a familiar backyard vegetable — grown on bamboo trellises in home gardens from Ilocos to Mindanao — though it has never achieved the commercial scale of crops like sitaw or monggo despite its superior nutritional profile.

How to Plant Sigarilyas

Propagation method: Seed (direct sow)

Germination time: 7 to 14 days

Best planting season in the Philippines: June to August (onset of rainy season)

Step-by-Step Planting Guide

1. Select and prepare seeds. Collect mature, dried seeds from fully ripened sigarilyas pods — choose plump, undamaged seeds with a dark brown color. Soak the seeds in room-temperature water for 12 to 24 hours before planting. This softens the hard seed coat and dramatically improves germination rates. Some Filipino farmers also nick the seed coat with a knife or file for faster water absorption.
2. Install your trellis first. Before planting, set up a sturdy bamboo frame, wire trellis, or net support at least 2 to 3 meters tall. Sigarilyas is a vigorous climbing vine that needs vertical structure from the start. Use bamboo poles tied in an A-frame or lean-to configuration — this is the traditional Filipino method and provides excellent support. The trellis must be strong enough to bear the heavy weight of a fully productive vine loaded with pods.
3. Prepare the planting bed. Sigarilyas thrives in rich, well-drained soil with plenty of organic matter. Dig the planting area to a depth of 30 cm and mix in generous amounts of compost, aged animal manure, or vermicast. As a legume, sigarilyas fixes its own nitrogen, but it still benefits greatly from phosphorus and potassium — work in a handful of bone meal or wood ash per planting hole.
4. Sow seeds directly. Plant seeds 3 to 5 cm deep, spacing them 30 to 45 cm apart along the base of the trellis. Place two seeds per hole and thin to the strongest seedling after germination. Direct sowing is strongly preferred because sigarilyas has a sensitive taproot system that does not transplant well — seedlings moved after the first true leaves develop often suffer transplant shock and stunted growth.
5. Water consistently during establishment. Water generously immediately after planting and keep the soil consistently moist (but never waterlogged) during the germination period of 7 to 14 days. Once seedlings are established and actively climbing, water deeply two to three times per week. Apply a thick layer of rice straw or dried leaves as mulch around the base of each plant to conserve soil moisture during hot afternoons.
6. Train vines and harvest young pods. As seedlings grow, gently guide the young vines toward the trellis. Sigarilyas will naturally twine and climb once it contacts the support structure. Begin harvesting pods when they reach 10 to 15 cm in length — typically 60 to 75 days after planting. Harvest every two to three days during peak production to encourage continuous flowering and prevent pods from maturing and becoming tough.

Care Guide

Sunlight

Requirement: Full Sun

Sigarilyas requires full sun with at least 6 to 8 hours of direct sunlight daily for optimal growth and pod production. The vine grows vigorously in full tropical sun and will become leggy and produce fewer flowers if shaded. In the Philippine context, position the trellis in an open area of the garden away from large shade trees. South or west-facing walls and fences work well as trellis locations because they receive maximum afternoon sun.

Water

Frequency: 2 to 3 times per week

Water sigarilyas deeply and consistently, especially during the dry season and when pods are developing. The vine has moderate water needs — more than drought-tolerant crops like malunggay, but less demanding than water-loving vegetables like kangkong. During the Philippine rainy season (June to October), natural rainfall is usually sufficient. In the dry months, water at the base of the plant in the morning to reduce leaf moisture and fungal risk. Mulch heavily to conserve soil moisture between waterings.

Soil

Type: Rich Loam, Sandy Loam

pH Range: 5.5 to 6.5 (slightly acidic)

Sigarilyas performs best in rich, well-drained loamy soil with high organic matter content. Unlike some legumes that tolerate poor soil, sigarilyas produces significantly more pods in fertile, well-prepared garden beds. The ideal Philippine soil is the deep, loamy volcanic soil found in many parts of Luzon and the Visayas. If your soil is heavy clay, amend it with generous amounts of rice hull, coconite (coco coir), and compost to improve drainage and aeration. Slightly acidic to neutral pH is ideal.

Humidity and Temperature

Humidity: 70 to 90%

Temperature: 25°C to 35°C

Sigarilyas thrives in the warm, humid conditions of the Philippine lowlands. It grows best at temperatures between 25°C and 35°C — matching the year-round climate of most Philippine provinces. The vine is sensitive to cold and will not tolerate temperatures below 15°C, which makes it unsuitable for high-altitude locations like Baguio. High humidity promotes vegetative growth, while the slightly drier conditions of the amihan season (October to February) can trigger heavier flowering — coincidentally matching the short-day requirement for bloom.

Fertilizer

Because sigarilyas is a nitrogen-fixing legume, it requires less nitrogen fertilizer than most vegetables. Focus instead on phosphorus and potassium to support flowering and pod development. Apply a low-nitrogen fertilizer like 5-10-10 or simply side-dress with compost and wood ash every 3 to 4 weeks during the growing season. Avoid high-nitrogen fertilizers, which will produce excessive leafy growth at the expense of flowers and pods. An occasional foliar spray of seaweed extract helps boost micronutrient availability.

Pruning

Sigarilyas vines benefit from pinching the growing tips once they reach the top of the trellis. This encourages lateral branching and more flowering nodes along the vine. Remove any dead or yellowing leaves regularly to improve air circulation and reduce disease pressure. After the main harvest period ends, cut the vine back to about 30 cm above the ground — it will regrow vigorously for the next season from the established root system and tuberous roots.

Growing Medium Options

Sigarilyas is best grown directly in the ground in rich, well-drained soil. Its vigorous root system — which includes nitrogen-fixing nodules and starchy tubers — requires deep, unrestricted soil to develop properly. Container growing is possible in very large pots (at least 60 cm deep and 45 cm wide) but will significantly reduce yields compared to ground planting. Hydroponic cultivation is not practical for sigarilyas due to the extensive root system, heavy vine weight, and the symbiotic relationship with Rhizobium bacteria that requires a soil environment. For urban growers with limited ground space, a large grow bag or raised bed positioned against a sunny wall with a sturdy trellis is the best alternative to direct ground planting.

Edible Uses and Nutrition

Edible parts: Pods, Leaves, Flowers, Tubers, Seeds (all parts)

Culinary Uses

Sigarilyas is one of the most versatile vegetables in Filipino cooking, with each part offering a different culinary application. The young pods — harvested at 10 to 15 cm when the wings are still tender — are the most commonly eaten part. They are sliced diagonally and prepared as ginisang sigarilyas (sauteed with garlic, onion, tomato, and a splash of bagoong), added to gising-gising (a creamy, spicy Bicolano dish cooked in coconut milk with labuyo chili and shrimp paste), or tossed into pinakbet alongside other native vegetables. Young pods can also be eaten raw — sliced thin, they add a pleasant crunch to salads with a flavor reminiscent of snap peas with a slight nutty undertone.

Beyond the pods, Filipino cooks use the young leaves and tender shoot tips as a leafy green, blanched or sauteed like kangkong. The pale blue flowers are edible and make an attractive addition to salads. The tuberous roots — which develop on mature plants — are boiled, roasted, or sliced and fried like potato chips, offering a nutty, slightly sweet flavor with remarkably high protein content. Mature seeds are dried and roasted like peanuts, or ground into flour for enriching baked goods.

Nutritional Highlights

Harvest time: 60 to 75 days after planting for first pod harvest; pods produced continuously for 3 to 4 months during the flowering season.

Storage: Fresh pods keep 3 to 5 days when refrigerated in a perforated plastic bag. Do not wash before storing as moisture accelerates spoilage. For longer preservation, blanch sliced pods for 2 minutes, ice-bath, and freeze for up to 3 months. Mature seeds should be thoroughly dried and stored in airtight containers in a cool, dry place for up to one year.

Air Quality and Nitrogen Fixation

While sigarilyas is not primarily grown for air purification, it contributes positively to the garden ecosystem through its nitrogen-fixing ability. As a legume, sigarilyas harbors Rhizobium bacteria in specialized root nodules that convert atmospheric nitrogen (N2) into plant-available ammonium. This biological nitrogen fixation enriches the surrounding soil naturally, reducing or eliminating the need for synthetic nitrogen fertilizers in the garden.

CO₂ absorption: Moderate

A healthy, fully-grown sigarilyas vine covering a 2-by-3-meter trellis provides substantial green leaf coverage that actively photosynthesize and absorb carbon dioxide. While not comparable to a mature tree, the dense vegetative canopy of a productive sigarilyas trellis contributes meaningful CO₂ absorption within a small urban garden space. Additionally, the nitrogen it deposits in the soil benefits subsequent crops planted in the same bed, making sigarilyas an excellent rotation crop in Philippine vegetable gardens. After the harvest season, the vines can be cut and incorporated into compost or directly dug into the soil as green manure.

Toxicity and Safety

Humans: Non-toxic (all parts edible)

Pets: Non-toxic — safe around cats and dogs

Sigarilyas is entirely non-toxic and safe for human consumption and animal contact. All parts of the plant — pods, leaves, flowers, tubers, and seeds — are safe to eat when prepared appropriately. Young pods and leaves can be eaten raw or lightly cooked. Mature seeds should be cooked before consumption (boiled, roasted, or fried) as they contain trypsin inhibitors that are deactivated by heat, similar to other legumes like soybean. The vine itself is not known to cause skin irritation or allergic reactions in handling. Sigarilyas is safe to grow in gardens with children and pets, and the plant has no reported toxic effects on poultry, goats, or other backyard animals commonly found in Filipino households.

Common Pests and Diseases in the Philippines

Pests

• Bean pod borers — larvae that bore into developing pods, causing internal damage and making pods unmarketable. Inspect pods regularly and remove any showing entry holes. Apply Bacillus thuringiensis (Bt) spray as a biological control during heavy infestations.
• Aphids — soft-bodied insects that cluster on growing tips and young leaves, sucking sap and transmitting viral diseases. Control with neem oil spray or by encouraging natural predators like ladybugs and lacewings in the garden.
• Bean flies (Ophiomyia spp.) — small black flies whose larvae mine into stems near the soil line, causing wilting in young plants. Use yellow sticky traps and avoid planting in beds where beans were previously grown to break the pest cycle.

Diseases

• Powdery mildew — white fungal coating on leaves during dry, cool mornings. Improve air circulation by spacing vines properly on the trellis and remove affected leaves promptly. Spray with diluted baking soda solution as a preventive measure.
• Root rot — caused by waterlogged soil conditions, especially in poorly drained clay soils during the monsoon season. Ensure raised beds or mounded planting rows with good drainage. Avoid watering in the late afternoon when soil stays wet overnight.
• Leaf spot — circular brown spots on leaves caused by Cercospora and other fungal pathogens during prolonged humid weather. Remove and destroy infected leaves. Apply copper-based fungicide only in severe cases.